Hemolytic and Haemorrhagic diseases of newborn Flashcards
Newborns predisposition to vit. K deficiency
- this coagulation abnormality leads to serious bleeding
- transplacental trasfer of vitamin K is very limited during pregnancy
- storage of vit. K in liver is also very limited in newborns
- once the infantile gut is colonized with bacterial flora, microbial production of vit. K results in lower riks of bleeding related to deficiency
Vitamin K deficiency in breast fed infants
- breast milk is a poor source of vitamin K (1-4µg/l)
- recommended dietary intake is 1 µg/l/day
- exclusively breastfed infants have intestinal colonization with lactobacilli that do not produce vit. K
- reduced production of menaquinone (vit K2) increases neonatal risk of bleeding
Vitamin K dependent proteins
- Factor II (prothrombin)
- Factor VII (Proconvertin)
- Factor IX (Thromboplastin component)
- Factor X (Stuart factor)
- Protein C and S
- Protein Z
Vitamin K effect on clotting cascade
If not enough vitmain K present –> cltting factors are not synthesized enough –> clotting cascade is not functioning
Clotting cascade intrinsic pathway
Damaged Surface –> kininogen, Kallikrein
- -> XII –> XIIa
- -> XI –> XIa
- -> IX –> IXa
- -> VIIIa helpts X turn to Xa
- -> Xa activates Va
- -> Va turns protrombin to thrombin
- -> thrombin turns fibrinogen to fibrin
- -> with XIIIa cross-linked fibrin clot produced
Clotting cascade extrinsic pathway
Traume
- -> VII –> VIIa
- -> VIIa acitvated tissue factor
- -> tissue factor turns X to Xa
- -> Xa activates Va
- -> Va turns protrombin to thrombin
- -> thrombin turns fibrinogen to fibrin
- -> with XIIIa cross-linked fibrin clot produced
Primary hemolytic disease of newborn (HDN)
- often fatal
- diffuse hemorrhage in otherwise healthy infant
- in first week of life
- mostly in low weight babies
- low levels of prothrombin and other vit K dependent clotting factors
Clinical Manifestation of pirmary HDN
bleeding in
- GI
- Urinary tract
- umbilical stump
- nose
- scalp
- intracranial
- injection sites
- shock
- death
Prophylactic use of vitamin K
- intramuscular administration within the first 6 hours after birth are effective in preventing both early and late HDN
Treatment of vitamin K deficiency
- vit K1 (phytonadione) for prothrombin, proconvertin and thromboplastin component and stuart factor
- coagulation factors should increase in 6-12 hours after PO dosing and 1-2 hours after parenteral
- for life threatening hemorrhages along with IV administration of Vitamin K, 10-20ml per kg body weigzht fresh frozen plasma should be adminstered
- if blood loss > 20% and there is evidence of shock: immediate blood transfusion
Definition of Hemolytic disease of newborn (HDN)
Condition in which fetus or neonate’s red blood cells are destroyed by IgG antibodies produced by mother
Rh hemolytic disease of the newborn
- mother is Rh negative
- Rh sensitization is not likely in first pregnancy
- in next pregnancy: mother’s antibodies cross the placenta then reacts with an RBC antigen to fight the Rh positive cells in the baby’s body
- antigen-antibody interaction occurs
- sensitization of baby’s RBC by mother’s IgG antibody causes baby’s RBC to be destroyed
- Ab coated RBCs are removed from fetal corculation by the macrphages of the spleen and liver
- anemia willstimulate bone marrow t produce immature RBC –> erythroblastosis fetalis
Clinical features of Rh hemolytic disease of the newborn
LESS SEVERE
- mild anemia
SEVERE
- icterus gravis neonatorum (Kernicterus)
INTRAUTERINE DEATH
- hyrops fetalis –> edematous, ascites, bulky swollen and friable placenta because extravascular hamolysis with extramedullary eryhthorpoiesis and hepatic and cardiac failure
Kramer’s rule
Evaluation of the degree of jaundice in newborn
1st zone: yello head, neck, sclera 2nd zone: yellow trunk 3rd zone: hypogastric region 4th zone: extremities 5th zone: all the body, severe
Prevention of Rh hemolytic disease of the newborn
- all non.sensitized Rh D-negative women should be given anti-d immunoglobulin at 28 adn 34 weeks of gestation
- at birth, if baby is Rh- –> no further treatment
- if baby is Rh+ –> porphylactic anti-D should be administered within 72h of delivery
Treatment of Rh hemolytic disease of the newborn
UNBORN BABY
- intrauterine blood transfusion
NEWBORN BABY
- phototherapy
- exchange transfusion
- intravenous immunoglobulun (IVIG) to prevent destruction of RBC
Intrauterine blood transfusion
- to replace fetal RBCs that are being detroyed by the Rh sensitized mother’s immune system
- is meant to keep fetus healthy until it is mature enough the be delivered
- in severely affected fetus: tranfusions every 1-4 weeks
Management of indirect hyperbilirubinemia
- visual assessment
- blood level monitoring at 24 h of life or sooner
- interpretation of risk levels and need for treatment
- -> phototherapy
- -> exchange transfusions
- -> IVIG
- -> Phenobarbital
Transcutaneous bilirubinometry
- measures the bilirubin level by contact with skin
- does not reflect exact bilirubin levels but gives a general idea about bilirubin levels in the blood
Bhutani Curve
If the baby is in the range of the curve, phototherapy should start
The earlier the hyperbilirubinemia starts, phototherapy should also start
Important factors in efficacy of phototherapy
- distance
- skin area exposed
- irradiance
- spectrum of light
Exchange blood transfusion
- removes sensitized cells
- reduces level of meternal antibody
- removes about 60% of plasma bilirubin, resulting in clearnace of about 30-40% of total bilirubin
- corrects anemia
- replacement with donor plasma restores albumin and any needed coagulation factors
- usually two volume exchanges are needded as bilirubin from tissues will return to the blood stream
- first blood is taken from the baby, then transufison the blood (25 procedures)
Clinical outcomes of hyperbilirubinemia
- Deposits in skin and mucous membranes –> jaundice
- Unconjucated bilirubin deposits in the brain –> acute bilirubin encephalopathy
- Permanent neuronal damage –> kernicterus
ABO incompatibility
- most common cause of HDN
- with blood types A and B, isoimmunization does not occur because the naturally occurring antibodies are IgM, not IgG
- in type O mothers: antibodies are predominantly IgG, cross the placenta and can cause hemolysis in fetus
- HDN only occurs in 3%
- ABO can occur in first pregnancies
- clinical presentation usually less severe than with Rh disease
Diagnosis and treatment of ABO imcompatibility
- diagnosis and investigation are the same as Rh disease
- Treatment is by phototherapy and exchange transfusion
- no effective prevention against ABO incompatibility reaction
Differential diagnosis
- hemorrhage in the newborn
- failure of erythrocyte production in newborn
- conjugated hyperbilirubinemia
